The present invention is involved with the forming of a tray suitable for use in packaging foodstuffs and specifically suitable for packaging frozen foodstuffs.
In general there are currently used two basic types of cartons for packaging frozen foods. One type utilizes a lid and tray formed from a single blank and attached together along one edge. The tray and lid can be locked and sealed by interlocking parts or by the use of glue. Difficulties have arisen in handling such a carton in that the lid is always attached and therefore the operations of forming the tray and filling the tray are more complicated due to the free-swinging lid. In addition, in the case of the interlocking parts there is some chance that the interlock will fail permitting the carton to come apart. The advantage of using such a tray is that foodstuffs can be inserted easily into the large flat open-topped tray. In addition, where the tray is more or less watertight, liquid foodstuffs can also be packed.
The other type of carton used today is the tubular type wherein the carton is formed with both ends open usually with a glue joint running lengthwise of the carton. End flaps are formed integral with the body portion and by closing one end, foodstuffs can be packed into the other end prior to closing. The disadvantage of this type of carton is that certain foodstuffs cannot be efficiently packed therein from one open end. For instance, asparagus or other foodstuffs packed in a parallel manner cannot be inserted through one end of the carton. Therefore these cartons will accept free-flowing products but will not accept such products as asparagus, broccoli, cauliflower, et cetera.
The present invention makes use of the advantages of a carton which incorporates a tray which is waterproof and can be easily packed with foodstuffs. The carton involves a separated tray and lid providing the advantages of ease of handling since only the tray is passed through the packing station and thereafter the lid is brought into engagement with and fixed to the tray. Because of the particular configuration of the lid and tray an overwrap can be done away with and the label printed directly on the lid and tray.
The apparatus embodying the present invention is directed to the forming of such cartons and trays made from such materials as paper, cardboard, plastic or like materials. Ordinarily where such trays are used in industries such as food packaging, the tray blanks are delivered to the place of usage and formed just prior to the time of filling. In other words, if food products are being packaged, the forming apparatus is positioned adjacent the filling machinery so that the trays are delivered directly from the forming apparatus to the filling station.
The reason for forming the trays immediately prior to use primarily involves the difficulty in storing and handling the tray once it is formed. Whereas the blank material stacks and stores easily and efficiently, the formed tray or carton does not. In addition, if the trays become flattened or otherwise deformed during transportation or storage, the subsequent filling machines might not handle them properly.
With the apparatus being located at the filling station, other factors become quite important. For instance, preferably the forming apparatus should be compact so as not to take up space which otherwise can be used for other purposes. In addition, with the high cost of such machinery and labor, it is increasingly important that the throughput be as high as practical. This reduces the number of tray forming machines necessary which both reduces the initial capital investment, the manpower needed for operation of the machinery and the space necessary to accommodate the tray forming.
Because of requirements for many different sizes of trays, it is also important to provide forming apparatus which is adaptable for handling various sizes of blanks and formed trays. Thus if one need only change the mandrels and adjust the other guide widths, et cetera, to change the size of the trays handled within the limits of the handling capabilities of such apparatus, the capital investment is reduced by requiring fewer machines for a given installation. For instance, in food processing where the products can be seasonal and can require different size trays, it is very economical to utilize the same tray-forming apparatus for different forming operations.
In accordance with the foregoing, it is the primary purpose of this invention to provide an improved apparatus for the formation of trays or cartons from blank material.